Cycloaddition of CO2 to epoxides catalyzed by polyaniline salts

The catalytic activity of polyaniline-HX (X=I, Br, Cl) (PANI-HI, PANI-HBr, PANI-HCl) for the cycloaddition of CO2 to propylene oxide (PO) to produce propylene carbonate (PC) was studied for the first time. It was shown that all the PANI salts were active for the reaction, and PANI-HI was most active and selective. On the basis of the preliminary results, the effect of the reaction conditions on the cycloadditions of CO2 to propylene oxide and epichlorohydrin was further investigated by using PANI-HI as the catalyst. The results indicated that the optimized temperature was around 115 degrees C. The maxima occurred in yield versus pressure curves at about 5 MPa for both substrates. Complete conversion was achieved in 3 h for epichlorohydrin and 6 h for propylene oxide at 115 degrees C and 5 MPa. With propylene oxide as the substrate, the reusability of PANI-HI was evaluated and no loss of catalytic activity was detectable after the catalyst had been reused five times. The catalyst was characterized by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), which provided further evidence for the high stability of the catalyst. We believe that the catalyst has great potential for industrial applications because it has some unusual advantages, such as its easy preparation, high activity, selectivity, stability, low cost, and simple separation from products.     

Salen-complex-mediated formation of cyclic carbonates by cycloaddition of CO2 to epoxides

Metal complexes of salen ligands are an important class of compounds, and they have been widely studied in the past. Among their successful catalytic applications, the synthesis of cyclic carbonates by the coupling reaction of epoxides with CO(2) has received increased attention; this is mostly due to the importance of using a greenhouse gas as a feedstock for the synthesis of useful molecules. Herein the most relevant past and present research surrounding this topic is presented.     

Synthesis of cyclic carbonates from epoxides catalyzed by metal–BINOL complexes

Synthesis of cyclic carbonates from CO₂ and terminal epoxides catalyzed by Mg, Ca and In BINOL complexes was achieved without organic solvents. Effects of temperature, CO₂ pressure, reaction time and co‐catalyst on the cycloaddition were investigated. Propylene carbonate was obtained under a CO₂ pressure of 1.2 MPa within 10 hours in a yield of 98% catalyzed by Ca–BINOL at 120°C. The order of catalytic activity of the metal center is Ca > In > Mg. Copyright © 2014 John Wiley & Sons, Ltd.     

Titanocene dichloride/KI: an efficient catalytic system for synthesis of cyclic carbonates from epoxides and CO2

Titanocene dichloride (Cp₂TiCl₂)/KI was developed to be an efficient catalytic system for the cycloaddition of CO₂ to epoxides to synthesize relevant cyclic carbonates from epoxides and CO₂. Various influencing factors on the coupling reaction, such as co‐catalyst, temperature, CO₂ pressure and reaction time, were investigated. The optimal reaction conditions were KI as co‐catalyst, 150 °C reaction temperature, 12 atm CO₂ pressure and 4 h reaction time using THF as solvent for the synthesis of propylene carbonate in 98% yield. Copyright © 2013 John Wiley & Sons, Ltd.     

二甲基烯丙基胺/溴代烷烃系列季铵盐的合成与表征

以溴代烷与二甲基烯丙基胺(DMAA)为原料合成了二甲基烯丙基类季铵盐;探讨了反应温度、原料配比、反应时间及溶剂对反应产率的影响,确定了最佳合成条件;并采用红外光谱仪、核磁共振谱仪(1 H NMR)及质谱仪表征了产物的结构.     

Heterocyclization of amino alcohols into saturated cyclic quaternary ammonium salts

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溴化苄基取代吡啶类季铵盐的制备和抗菌性能

抗菌材料和抗菌制品的研究与应用一直是世界各国研究的重要课题~([1-3]),其中有机抗菌剂占据主要地位.季铵盐是研究比较多的一类有机抗菌剂,它们表现出良好的物理性质,如胶束浓度低,黏弹性好和溶解性强~([4]),同时此类抗菌剂具有强效的抗菌作用~([5]),引起了人们的极大兴趣.季铵盐广泛应用于医药、卫生、食品、饲料工业、农业、纺织、塑料、橡胶、造纸、水处理、油田开采、涂料、日常生活等多种领域~([6-10]).     

Cycloaddition of epoxide and CO2 to cyclic carbonate catalyzed by VO(IV) porphyrin

The cycloaddition of epoxide and CO₂ to synthesize cyclic carbonate catalyzed by VO(IV) porphyrin was achieved under 1.4 MPa at 150°C. The effects of reaction temperature, time, CO₂ pressure, co‐catalyst and porphyrin framework were investigated. The catalytic results showed that moderate to high yields of cyclic carbonates were obtained under the optimal reaction conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

Copolymerization of carbon dioxide and propylene oxide catalyzed by two kinds of bifunctional salen-cobalt(III) complexes bearing four quaternary ammonium salts

Two new bifunctional salen-cobalt(III) complexes were synthesized, which consist of salicylaldehyde bearing four quaternary ammonium salts and two different diamines. The copolymerization results indicated that decreasing temperature is advantageous for both the complexes. Of both the diamines, the complex 9 with o-diaminobenzene has a higher catalytic effect compared to complex 6 with 1,2-diaminocyclohexane. The catalytic effect of complex 9 is over 3.5 times than that of complex 6 at a temperature of 30°C. The research of P_CO2 on the copolymerization revealed that the first-rank pressure was at 2 MPa for the two complexes. The highest turnover number are under conditions of T = 30°C, P_CO2 = 2 MPa, and t = 24 hr. Differential scanning calorimeter curves indicated that poly(propylene carbonate) (PPC) by complex 9 has the highest Tg of 54.2°C. DTGA curves showed that there were two thermal degradation peaks, the first is for the ester bond, and the second is for the C–C bond.     

乙酸盐上二氧化碳和二醇合成环状碳酸酯

在乙腈体系中,以不同的乙酸盐作催化剂,研究了CO2与二醇合成环状碳酸酯的反应.乙腈在反应过程中不仅是溶剂,而且还起到了脱水剂的作用,促进了反应的进行.以1,2-丙二醇为反应物对催化剂进行筛选,发现无水乙酸锌具有最高的催化活性.在无水乙酸锌上考察了二氧化碳和不同二醇的反应,结果表明,五元环碳酸酯的产率明显高于六元环碳酸酯,其中碳酸丙烯酯的产率最高.以1,2-丙二醇为反应基质,无水乙酸锌为催化剂,确定了最佳反应条件,1,2-丙二醇100 mmol,乙睛10 mL,催化剂2.5 mmol,反应压力10 MPa,温度170 ℃,反应12 h.在此条件下,碳酸丙烯酯的产率达到了24.2%,1,2-丙二醇的转化率为38.9%.     

Synthesis and application of novel carbohydrate-based ammonium and triazolium salts

The synthesis of nine new carbohydrate-based quaternary ammonium salts and two new triazolium salts starting from d-glucose has been accomplished. Our synthesis utilized the regio- and stereoselective ring opening reaction of 2,3-anhydro sugars by nucleophilic reagents to afford the key intermediates. In these new types of phase transfer catalysts, the ammonium and triazolium functions are directly attached to the carbohydrate scaffold in different positions (2-, 3-, 6-positions of the sugar). The efficiency of the altrose- and glucose-based quaternary salts were tested in the alkylation of N-(diphenyl) methylene glycine tert-butyl ester with benzyl bromide. To our knowledge this is the first example when sugar-based quaternary ammonium or triazolium salts were used successfully as phase transfer catalysts. The enantiomeric recognition ability of the synthesized salts towards racemic Mosher’s acid silver salt was also investigated by ¹⁹F NMR spectroscopy.     

Cyclic carbonate synthesis from epoxides and CO2 over cyanocobalamin/n‐Bu4NI

The synthesis of cyclic carbonates from epoxides and carbon dioxide catalyzed by cyanocobalamin and n‐Bu₄NI system was achieved under 0.8 MPa CO₂ pressure at 140°C without organic solvents. Propylene carbonate was obtained in 99% yield within 6 h under the optimized reaction conditions. The cyanocobalamin catalyst could be recycled with water and retained moderate catalytic activity. Copyright © 2012 John Wiley & Sons, Ltd.     

Coupling reactions of CO2 with neat epoxides catalyzed by PPN salts to yield cyclic carbonates

The off-the-shelf reagent PPN+Cl- and PPN-manganese carbonylates [PPN]+[Mn(CO)4L]- (L = CO, PPh3) are good catalysts for the coupling reactions of CO2 with neat epoxides without the use of organic solvents to afford cyclic carbonates. PPN salts with weak nucleophilic anions such as PPN+BF4- and PPN+OTf- are, however, inactive for the coupling reactions.     

Immobilization of Ionic Liquid on a Covalent Organic Framework for Effectively Catalyzing Cycloaddition of CO2 to Epoxides

Transforming CO₂ into value-added chemicals has been an important subject in recent years. The development of a novel heterogeneous catalyst for highly effective CO₂ conversion still remains a great challenge. As an emerging class of porous organic polymers, covalent organic frameworks (COFs) have exhibited superior potential as catalysts for various chemical reactions, due to their unique structure and properties. In this study, a layered two-dimensional (2D) COF, IM4F-Py-COF, was prepared through a three-component condensation reaction. Benzimidazole moiety, as an ionic liquid precursor, was integrated onto the skeleton of the COF using a benzimidazole-containing building unit. Ionization of the benzimidazole framework was then achieved through quaternization with 1-bromobutane to produce an ionic liquid-immobilized COF, i.e., BMIM4F-Py-COF. The resulting ionic COF shows excellent catalytic activity in promoting the chemical fixation of CO₂ via reaction with epoxides under solvent-free and co-catalyst-free conditions. High porosity, the one-dimensional (1D) open-channel structure of the COF and the high catalytic activity of ionic liquid may contribute to the excellent catalytic performance. Moreover, the COF catalyst could be reused at least five times without significant loss of its catalytic activity.     

A kinetic study on the reaction between glycidyl vinyl ether and carbon dioxide with quaternary ammonium salts as catalyst

The kinetics of the reaction between glycidyl vinyl ether (GVE) and carbon dioxide has been studied by using quaternary ammonium salts as catalyst. The catalysts having larger cations and more nucleophilic counter-anions showed higher activity. In a semi-batch reactor where CO₂ is continuously supplied, the reaction is first order with respect to the concentration of GVE. In a high pressure batch reactor, the reaction is first order with respect to both GVE and CO₂ and second order overall. In the latter case, a simple method to evaluate the rate constant and Henry's constant is also proposed.     

CO2 Fixation with Epoxides under Mild Conditions with a Cooperative Metal Corrole/Quaternary Ammonium Salt Catalyst System

The cooperative catalytic activity of several metal corrole complexes in combination with tetrabutyl‐ammonium bromide (TBAB) has been investigated for the reaction of epoxides with CO₂ leading to cyclic carbonates. It was found that the use of just 0.05 mol % of a manganese(III)corrole with 2 mol % TBAB exhibits excellent catalytic activity under an atmosphere of CO₂.     

聚合物负载季鏻盐催化 CO2 与环氧化物的环加成反应

 制备了聚合物负载的季鏻盐催化剂, 并用于 CO₂ 与环氧氯丙烷环加成反应中. 采用红外光谱、热分析、原子吸收光谱和扫描电子显微镜等手段测定了催化剂的结构、热性能、磷元素含量和表面形貌等. 考察了 CO₂ 压力、温度、催化剂用量和反应时间等对环加成反应性能的影响. 结果表明, 在催化剂用量为 0.09 g, CO₂ 压力为 4.5 MPa, 于 150 ^oC 反应 6 h 时, 3-氯甲基环碳酸酯收率可达 97.7%, 选择性大于 99%. 且催化剂易分离回收, 重复使用 5 次后产物收率和选择性没有明显下降. 同时探讨了该催化剂上 CO₂ 环加成合成环碳酸酯的可能机理.     

Hetero‐ and homo‐leptic Ru(II) catalyzed synthesis of cyclic carbonates from CO2; Synthesis,spectroscopic characterization and electrochemical properties

Based on the a ligand BDPPZ [(9a,13a‐dihydro‐4,5,9,14‐tetraaza‐benzo[b]triphenylene‐11‐yl)‐phenyl‐methanone] (1) and its polypyridyl hetero‐ and homoleptic Ru(II) metal complexes, [Ru(bpy)₂L](PF₆)₂ (2), [Ru(phen)₂L](PF₆)₂ (3), [Ru(dafo)₂L](PF₆)₂ (4), [Ru(dcbpy)₂L](PF₆)₂ (5) and [RuL₃](PF₆)₂ (6) (where, L = ligand, bpy = 2,2′‐bipyridine, phen = 1,10‐phenantroline, dafo = 4,5‐diazafluoren‐9‐one and dcbpy = 3,3′‐dicarboxy‐2,2′‐bipyridine), have been synthesized and characterized by elemental analysis, UV–vis, FT‐IR, ¹H and ¹³C‐NMR spectra (for ligand), molar conductivity measurements and X‐ray powder techniques. The electrochemical parameters of the substituted ligand and its polypyridyl hetero‐ and homoleptic Ru(II) metal complexes are reported by cyclic voltammetry. UV–vis spectroscopy is used to compare the differences between the conjugated π systems in this ligand and its Ru(II) metal complexes. The polypyridyl hetero‐ and homoleptic Ru(II) metal complexes also tested as catalysts for the formation of cyclic organic carbonates from carbon dioxide and liquid epoxides which served as both reactant and solvent. The results showed that the [Ru(L)₃](PF₆)₂ (6) complex is more efficient than the other Ru(II) complexes for the formation of cyclic organic carbonates from carbon dioxide. Copyright © 2010 John Wiley & Sons, Ltd.     

Mg(OH)Cl/KI as a Highly Active Heterogeneous Catalyst for the Synthesis of Cyclic Carbonates from CO2 and Epoxides under Solvent‐Free Conditions

The combination of magnesium hydroxyl chloride [Mg(OH)Cl] with KI could efficiently catalyze the coupling reaction of carbon dioxide with epoxides to give the corresponding cyclic carbonates in good to excellent yields (75.0% –98.3%) and high selectivity (99.6%) in the absence of organic solvents. The heterogeneous catalyst Mg(OH)Cl/KI could be reused at least six times almost without loss of the catalytic activity. The influence of some key factors (such as molar ratio of Mg(OH)Cl to KI, temperature, reaction time and CO₂ pressure) on the reaction was also discussed.